Abrasives are commonly used in a wide variety of fields for abrading material from a workpiece. The workpiece may be made of a material such as wood, plastic, metal, or glass, and typically may have an excess of such material or an undesirable surface finish, or both. In either case, or for other similar applications, an abrasive article is typically used to abrade the surface of the workpiece until the excess material has been removed or the surface finish has been refined, or both. Two popular types of abrasives are nonwoven abrasives and coated abrasives, and either may be provided with a range of surface characteristics to abrade a workpiece in a desired manner.
For a typical abrading process, a variety of abrasive articles may be used to provide a progressively finer finish. These abrasive articles are typically used in series, wherein the abrasive articles used initially remove deep scratches and excess material, and later abrasive members refine and finish the surface as desired. For example, a cast or molded part may have an excess of material in one or more locations as well as a relatively rough surface finish. A worker may first use a coarse abrasive to remove most of the excess material and to abrade away any deep scratches in the surface finish. The worker may then change tools, and use a finer grade abrasive to remove more of the excess material and to refine the surface further. Finally the worker may use a still finer grade abrasive member to remove minor imperfections and scratches from the surface of the workpiece. This method is known as the "grade sequence" method of abrading, and is widely used for a variety of applications.
Abrading, as that term is used herein, includes not only sanding, grinding, and macroscopic surface refinishing, but also buffing, polishing, and other types of microscopic surface finishing and refinement as well. Buffing, as that term is used herein, is the process used to remove small scratches left by the fine grade abrasive used in the final sanding step. Polishing, as that term is used herein, is the process used to remove any swirl marks left by the buffing member. Both buffing and polishing typically require the addition of certain compounds to enhance and refine the surface finish. Hence a worker may use one or more abrasive articles sequentially to grind away excess material in the manner described above, and may use one or more buffing and polishing members sequentially to produce the appropriate surface finish on the workpiece.
Although sequential abrading processes like those described above are generally effective in producing a workpiece of a desired size and finish, these processes may require many different tools. If, for instance, a worker uses two sanding or grinding steps, a buffing step and a polishing step, a total of four different tools may be required. The worker must then exchange and manipulate these four tools during the process of abrading a single workpiece. In the course of a single working shift, each tool may be picked up and set down dozens or even hundreds of times, which results in a substantial amount of time used to manipulate the different tools.
It is therefore desirable to provide an abrading article that includes more than one abrasive surface, to enable a worker to complete more than one abrading step with each tool.